One of the main advantages of the Tesla Model S is its relative freedom from “range anxiety,” at least in the 85-kilowatt-hour battery pack of the higher-end versions.

Rated by the EPA at 265 miles, that range compares to ratings of 62 to about 90 miles in less expensive plug-in electric cars.

And the Model S vehicles offers even greater freedom for road trips via the national (and international even) proprietary Supercharger system funded and built entirely by Tesla Motors for its owners.

DON'T MISS: Tesla Model S Cross-Country Trip, Without (Many) Superchargers

For early Tesla Model S85 owners, the first groups of these Supercharger sites were clustered around the company's factory in Fremont, California, and elsewhere in the state.

Teslas got their first and strongest foothold in California, and one of the first six Supercharger sites was at the Folsom Outlet Mall to allow Bay Area Tesla drivers to get to the ski vacations and gambling haunts of Lake Tahoe and Reno.

Tesla Supercharger locations in the United States, March 2015

Tesla Supercharger locations in the United States, March 2015

Each Supercharger site has six or more charging connectors, and is advertised as providing "up to 170 miles of added range in 30 minutes."

The caveat, of course, is the "up to," as I've never seen more than 140 miles in half an hour with my 2013 Tesla Model S.

But that 170-mile figure was usually achieved in 45 minutes, and I've Supercharged more than 30 times now.

ALSO SEE: Road Trips In A Tesla Model S Electric Car: Lessons Learned (Dec 2013)

Often on major trips, I'd stay long enough to top off the battery for a full-range charge (272 miles in my S85).

Use of the Supercharger network is free forever as part of your Tesla purchase.

And it makes the growing network of sites a major part of Tesla’s ability to provide an electric car that can serve as a household's only vehicle for all driving needs.

Tesla Supercharger fast-charging system for electric cars

Tesla Supercharger fast-charging system for electric cars

On the world stage, Tesla now reports 396 Supercharger stations with more than 2,150 individual chargers.

For Tesla's main market in the United States, the growth of these charging stations has been quite dramatic over the last 12 to 18 months.

And it continues, in fact to the point where this article had to be updated twice over the few days it was being edited.

From January through April last year, Tesla opened 39 Supercharger sites with a total of 104 charging points.

Tesla Supercharger site in Dorno, Italy, photo by problemidiricarica.wordpress.com/

Tesla Supercharger site in Dorno, Italy, photo by problemidiricarica.wordpress.com/

Then from May through August, it added another 20 sites with 122 charging cables.

Then the pace ramped up from September through December, with another 37 sites encompassing 264 charging points.

MORE: 2014 Tesla Model S P85D: First Drive Of All-Electric AWD Performance Sedan

And through yesterday, 29 more were opened with more than 180 additional cables.

Despite some early missed deadlines for getting Supercharger sites up and running, it seems clear that Tesla is following through on its promise to offer a national network of Superchargers.

2013 Tesla Model S at Supercharger station on NY-to-FL road trip [photo: David Noland]

2013 Tesla Model S at Supercharger station on NY-to-FL road trip [photo: David Noland]

More accurately, it's now a North American network: Canada too has seen the installation of 12 charging stations with a total of 62 chargers during this same time period.

And many more are permitted and/or under construction throughout the United States and Canada.

For the latest details on Supercharger sites, the Teslarati fan site maintains a summary of Tesla Charging stations.

The same information can also be found on Tesla's own site.

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